The present invention relates to a position measuring instrument for scanning or tracking a photoreceiver as a target to be measured, and more particularly to an automatic position detection instrument capable of emitting distance measuring light and tracking light while turning directions of the distance measuring light and the tracking light so that three-dimensional measurement of a light receiving position is performed, and further capable of transmitting measured data to a photoreceiver provided on a target.
Heretofore, a total station is used for three-dimensional position measurement and settings. The total station has functions of measuring a distance and an angle and then outputting measured values as electric data. When performing the measurement, the total station is first placed at a reference position before placing a target at a point of measurement. Next, the target is collimated by the total station to measure a horizontal angle and an angular height. Then, a distance to a reflecting prism (corner cube) provided on the target is measured, and thereby distance data can be obtained.
Distance and angle data which have been measured are stored in an internal memory of the total station. In addition, the distance and angle data measured are output to an external memory device or a computer as data of survey work as the need arises. FIG. 7 is a diagram illustrating survey work using a total station. The total station (1000) is placed at a reference position. A target (2000a) is attached to a pole (3000a). The pole (3000a) is placed at a point of measurement by an operator (4000).
The total station (1000) comprises the following: a telescope unit; a stand for freely supporting up and down rotation of the telescope unit; a base for freely supporting horizontal rotation of the stand; and a leveling unit that is provided on the lower part of the base, and that is used to level a slant of a main body of the total station (1000) before securing it to the top of a tripod. It is to be noted that circuits, and the like, used for the distance measurement and the angle measurement are built into the total station (1000).
The operator on the total station (1000) side rotates the telescope unit up and down and right and left to find the target (2000a) at a collimation center, and then obtains a horizontal angle, an angular height, and a distance relative to the reference position.
However, in the survey work where the conventional total station (1000) is used, at least two operators, that is to say, an operator on the total station 1000 side and an operator for placing the target (2000a), are required. The number of operators increases with increase in the number of targets (2000a). However, it is difficult to measure many targets (2000a) in a moment. It is practically impossible. To be more specific, measuring time in response to the number of targets (2000a) is required for the operator to collimate the target (2000a) by use of the telescope unit, and further to perform measurement. As a result, work efficiency cannot be improved to a large extent, which was a problem.
In addition, when carrying out work concurrently in adjacent sites, each of which has a reference coordinate system different from each other, it is possible to carry out the work by use of one total station and a plurality of targets. However, every time a reference coordinate system of a measuring point changes, it is necessary to retry coordinate settings of the total station, or to switch between the coordinate systems. Accordingly, it is practically impossible to carry out the work concurrently.